It has been suggested that the basal ganglia play a role in postural reflexes and are important in postural fixation, as well as adjustments for the maintenance of equilibrium. Therefore, it is important to determine the activity of these cells in unanesthetized, unparalyzed monkeys making postural adjustments. In addition to information that should contribute to understanding the function of these nuclei, the proposed "wiring diagram" models of interconnections between nuclei of the basal ganglia can be tested in chronic monkeys by comparing the simultaneous activity of cells in different nuclei. Finally, there is insufficient information about how basal ganglia output reaches the spinal cord, and this is essential in understanding how the basal ganglia can affect motor control. Specific Aims: 1. In awake animals, to record the activity of neurons in nuclei of the basal ganglia during tilt-elicited postural adjustments. 2. To relate neuronal activity in these structures to electromyographic activity of axial and limb muscles during the postural adjustment. 3. To compare the activity in neurons of different nuclei of the basal ganglia as a test of the internuclear connection models proposed by data from acute experiments. 4. In acute experiments, to determine pathways uttilized in basal ganglia to spinal cord transmission by stimulating the internal globus pallidus in acute experiments on monkeys and (a) recording the changes in the activity and postsynaptic potentials.